This invention relates to a precision cover with a spout for closing a container of liquid or particulate product.
It relates more particularly to a precision cover with a spout in which the top of the cover forms a spout with a sliding seal that is acted upon by a spring whose motion is controlled by a pivoting opening lever.
Such closing covers should both perform the function of precision-metering cover and sealing cover. In certain applications, in particular during use of these covers for closing a paint container, it is necessary to be able to close the spout of the cover immediately and in a perfectly sealed manner to avoid any evaporation or drying of the paint. To obtain a precise metering, it is preferable to use, during the phase of opening the spout of the cover, a reduction ratio of the travel, namely a long travel of the lever combined with moving the seal of the spout a short way. However, if the movement of the lever remains proportional to the travel of the seal, it becomes necessary to use a long travel of the lever to obtain a complete opening of the spout, which should be sized to allow an adequate maximum flow rate. This proves as difficult for the operator to handle as it is cumbersome. As a result, the covers, such as those described in Patent FR-A-2,555,141, are not satisfactory for a small opening of the seal since it is difficult to adjust this opening because moving the lever a short way causes the seal to be moved a long way.
To overcome this problem, it was provided, in particular in the patents FR-A-2,474,632, WO 97/134775 and U.S. Pat. No. 5,413,257, to use a cover whose seal is equipped with an actuating device designed such that in closing position, the seal is kept in airtight contact on the section of the opening of the spout and such that, starting from this position, in a first phase, the seal slides on the section of the opening of the spout, and, in a second phase, the seal performs a swinging movement. The problem, in particular with a cover of the type of the one that is described in the U.S. Pat. No. 5,413,254, is that the paint tends to accumulate in the end zone of the seal close to the pivot axis such that eventually, the seal no longer closes the spout in an airtight manner.
The solutions with pivoting, such as those described in the patent FR-A-2,474,632, bring the dispersion of the paint to the surface of the cover. Actually, the seal of the spout is in contact with the paint such that when it is separated from the spout, drips occur and the paint spills on the outside of the spout and on the surface of the cover.